The disclosure relates to poly(arylene ether)/polyamide compositions.
Poly(arylene ether)/aliphatic polyamide compositions are widely used and the characteristics of the compositions are a result of, at least in part, the characteristics of the poly(arylene ether) and the polyamide. Despite their wide use compositions employing aliphatic polyamides can suffer from drawbacks such as undesirably low dimensional stability, and high moisture absorption. Attempts have been made to improve the physical property profile by altering the polyamide structure to include aromatic elements. Compositions employing these aliphatic-aromatic polyamides have improved many physical properties such as heat resistance, dimensional stability and water absorption but have diminished other desirable properties. For instance, many aliphatic-aromatic polyamides have melt temperatures above the degradation temperature of many polymers. Thus these aliphatic-aromatic polyamides cannot be blended with many polymers without causing at least partial degradation of the polymer. Some aliphatic-aromatic polyamides have a melt temperature less than the degradation temperature of many polymers but these polyamides usually have inadequate dimensional stability for most applications and blends employing them typically demonstrate poor dimensional stability as well.
Additionally, poly(arylene ether)/polyamide compositions typically have at least two immiscible phases and the physical properties of the composition can be affected by the morphology of the phases.
There is a growing need for polymers and polymer blends suitable for use in low pressure/low shear processes such as blow molding, sheet extrusion and profile extrusion. Low pressure/low shear processes are significantly different from high pressure/high shear processes such as injection molding. For example, profile extrusion requires that a polymer blend be forced through a shaped die (a profile) and maintain the extruded shape until cooled. The extruded shape may be further manipulated while the polymer blend is still warm through the use of shaping tools and the shaped profile must retain its shape after manipulation. Therefore blends employed in low pressure/low shear processes typically have fairly high melt viscosity (low melt flow indices) as well as high melt strength.
Formation of a multi-phasic polymer blend having high melt viscosity and high melt strength can be difficult because the high melt viscosity can have a negative impact on the morphological relationship between the phases with a resulting negative on physical properties such as melt strength and impact strength.
Accordingly there is a need for a poly(arylene ether)/aliphatic-aromatic polyamide composition having a combination of high melt viscosity, high melt strength and low water absorption.